A static longitudinal stability (SLS) system provides an unobtrusive airspeed hold function that reacts to the pilot control inputs into the flight control system and the measured states of the aircraft to engage and disengage smoothly without any explicit mode selection by the pilot. The SLS engages airspeed hold when the aircraft is close to trimmed, non-accelerating state. This logic allows the pilot to either fly close to a desired airspeed and let SLS engage, or trim the aircraft in an accelerating/decelerating maneuver and just wait for the SLS to capture a speed when longitudinal acceleration is small. The SLS is not dependant on the pilot specifically selecting this mode, but rather engages and disengages in response to flight control system status and how the aircraft is being maneuvered.